KR101579925B1

KR101579925B1 - Plated solid wire for metal active gas welding

Info

Publication number: KR101579925B1
Application number: KR1020140161674A
Authority: KR
Inventors: 김영천; 서지석
Original assignee: 현대종합금속 주식회사
Priority date: 2014-11-19
Filing date: 2014-11-19
Publication date: 2015-12-29

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid wire suitable for welding in an electroplating method, and more particularly, to a plated solid wire for MAG welding superior in wire feeding during welding.

Description

{PLATED SOLID WIRE FOR METAL ACTIVE GAS WELDING}

Conventionally, a technique of controlling the surface shape of a wire or attaching a lubricant to the surface of a wire has been used to improve arc stability and transmittance during welding by using a solid wire.

For example, in Patent Document 1, artificial grooves are formed on the surface of the wire in the lateral direction, and a liquid lubricant is filled between the grooves to improve the feedability. In Patent Document 2, sodium (Na), calcium (Ca) , Potassium (K), calcium (Ca), and their compounds at appropriate ratios to improve arc stability and wire feedability. In Patent Document 3, citrate, halogen compound, phosphate, And the alkali metal is left on the surface of the wire by heat treatment in the atmosphere so as to improve the transmittance.

However, the above-mentioned prior arts have found problems such as artificial processing of wires, non-uniform coating of the compound coated on the wire surface, problem of the weldability of the welded part by the compound, and troublesome work requiring additional process such as heat treatment .

On the other hand, as another method for improving the transmittability of the solid wire, there has been used a copper-plated solid wire obtained by plating the surface of the solid wire in a copper plating bath.

Generally, copper-plated solid wires are produced by a pickling process, a primary drawing process, a plating process, and a secondary drawing process. In this case, the primary drawing process is a process for removing the fresh lubricant adhered to the surface of the wire rod, and the feed line subjected to the degreasing and the hand treatment passes through the pickling bath to remove the fine scale scale and the non-degreasing material before plating. In this case, if the plating quality of the wire surface, that is, the uniform plating thickness, the plating layer adhesion strength, etc., can not be ensured, the secondary wire drawing processability is significantly lowered However, there is a problem that the weldability and transmittance are deteriorated.

Therefore, in manufacturing a solid-plated solid wire, a manufacturing technique capable of ensuring excellent plating quality is indispensable in order to improve the productivity and secure the weldability and the feedability with excellent performance.

Japanese Patent Application Laid-Open No. 1981-144892 Japanese Patent Application Laid-Open No. 1995-299583 Japanese Patent Application Laid-Open No. 1994-218574

An aspect of the present invention is to provide a plated solid wire for mag welding which is excellent in weldability and feedability during welding as a solid wire for mag welding.

According to an aspect of the present invention, there is provided a solid wire for a mag-

A center line average surface roughness of 0.05 to 0.20 mu m and an average roughness of 0.8 to 2.5 mu m.

According to the present invention, not only a plating layer having a uniform thickness can be formed on the surface of a wire, but also a solid wire excellent in adhesion to plating can be provided, and the solid wire can be suitably used for mag welding.

Fig. 1 shows the results of observing the cross-section of the wire-plated layer of Inventive Example 12 (A) and Comparative Example 1 (B) with a scanning electron microscope (SEM, 1000 times).
Fig. 2 shows the results of observation of wire surface texture of Inventive Example 1 (A) and Comparative Example 10 (B) with a scanning electron microscope (SEM, 1000 times).
3 is a graph showing the results of observation of the surface texture of the wire with the addition of ammonium nitrate (NH ₄ NO ₃ ) in the plating baths of Inventive Example 5 (A) and Comparative Example 1 (B) with an electron scanning microscope .
4 shows the results of observing the surface of the plating layer with an optical microscope (100 times) after proceeding scratch evaluation of the wires of Inventive Example 2 (A) and Comparative Example 3 (B).
FIG. 5 is a graph of a welding monitoring test in the case of low current (150A) welding using the wires of Inventive Example 3 (A) and Comparative Example 9 (B).
Fig. 6 is a graph showing the measurement of the welding monitoring during the welding of the medium current 250A using the wires of Inventive Example 14 (A) and Comparative Example 4 (B).
FIG. 7 shows a graph of a welding monitoring test at the time of high current 350A welding using the wires of Inventive Example 15 (A) and Comparative Example 16 (B).

The plating process of the welding wire proceeds by passing the first drawn wire through a copper (Cu) plating bath to form a copper coating on the surface of the supply wire. At this time, a plating bath which does not satisfy the optimized range of plating bath concentration The surface of the passed wire has a problem that the adhesion of the plated film is not ensured and the plating quality such as dropping of the plated layer is deteriorated.

In addition, the plating quality of the wire during the above-described plating process depends on the plating solution concentration, that is, the P ratio and the pH value, and the additive concentration, and the adjustment of the plating thickness depends on the temperature of the plating bath and the deposition time, Can be adjusted accordingly. This is a result of controlling the atmosphere environment in which copper particles adhere to the wire surface. As a result, when the environment in the plating bath is lowered, the plating quality is lowered and the wire surface roughness is deteriorated.

In order to solve these problems, the present inventors tried to optimize plating conditions during wire plating, and to control the illuminance of the plated wire surface. As a result, it is possible to provide a solid wire capable of continuous welding work, since the plating layer is uniformly coated and the bonding force is excellent so that the plating layer does not come off during welding and does not inhibit the wire feedability by the dropped plating or residue. And the present invention has been accomplished.

Hereinafter, the present invention will be described in detail.

The solid wire for MAG welding according to one aspect of the present invention is plated and preferably has a center line average surface roughness of 0.05 to 0.20 탆 and an average roughness of 0.8 to 2.5 탆.

The surface roughness of the solid wire for welding is a measure of the adhesion of the plating, which means that when the surface roughness value is uniform, the plating adhesion is excellent.

In the case of the present invention, the center line average surface roughness is controlled to 0.05 to 0.20 탆 and the average roughness is controlled to 0.8 to 2.5 탆. When the center line average surface roughness value is less than 0.05 탆 and the average roughness value is less than 0.8 탆, The plating layer is likely to fall off during welding. On the other hand, when the values are more than 0.20 μm and 2.5 μm, respectively, the surface roughness of the plating layer is lowered as a whole, So that there is a problem that the transmittance is lowered.

In order to provide the solid wire having the surface roughness as described above, it is necessary to optimize the conditions for plating the wire. Particularly, in the present invention, the components in the plating bath are optimized and the plating bath temperature, Time and immersion time were optimized.

More specifically, in the present invention, it is preferable to add ammonium nitrate (NH ₄ NO ₃ ) in the plating bath at a concentration of 3 to 10 g / l in using the above copper plating bath for plating.

In the present invention, ammonium nitrate (NH ₄ NO ₃ ) is added to the copper plating bath at a constant concentration, and the plating adhesion during plating can be improved.

In a copper (Cu) plating bath, the thermochemical equilibrium of the copper metal and the cupric ion (Cu ⁺ ) in the quasi-equilibrium aqueous solution are converted to the cuprous oxide (Cu ₂ O). At this time, the copper film thickness increases with increasing copper ion concentration, but the physical properties and uniform adhesion of the copper film are decreased. However, ammonium nitrate (NH ₄ NO ₃ ) added in the present invention inhibits the overgrowth of copper (Cu) particles and improves the maximum permissible current density, thereby increasing the adhesion with Cu particles However, it is possible to improve the gloss of the wire surface, which leads to an increase in productivity.

If the concentration of ammonium nitrate (NH ₄ NO ₃ ) is less than 3 g / l, the improvement of the plating adhesion described above can not be sufficiently secured. On the other hand, when the concentration exceeds 10 g / The particles are overgrown, and the plating adhesion is lowered, and the gloss of the wire surface is lowered, so that the effect of addition can not be obtained.

Copper (Cu) and sulfuric acid (H ₂ SO ₄ ) are contained in the copper plating bath to which ammonium nitrate (NH ₄ NO ₃ ) has been added according to the above-mentioned conditions, in which 8 to 12 g / l and 25 to 35 g / l . &Lt; / RTI >

In addition, it is preferable that the plating bath having the above-described composition is a P ratio of 7.0 to 7.5 and a pH of 8.2 to 8.5.

Generally, weakly alkaline pyrophosphoric acid baths are free from corrosion of iron materials and are environmentally friendly ignorant plating processes, which impart copper (Cu) plating adhesion and high ductility plating films. If the P ratio in the plating bath is low, orthorhosphate (Na ₃ PO ₄ ) precipitates and the plating bath becomes contaminated and the quality of the plating deteriorates, thereby deteriorating the appearance quality due to overgrowth of Cu particles on the wire surface have. On the other hand, as the P ratio in the plating bath increases, the free P ₂ O ₇ ⁴ ^- complexes with the copper ion to form the complex [Cu (P ₂ O ₇ ) 2 ^-1 ] Plating adherence can be obtained, but if it is excessively high, the amount of orthophosphate is increased, which leads to brownish trabeculae, which is undesirable.

In addition, when the pH of the plating bath is low, there is a problem that the plating bath is decomposed by the hydration of pyrophosphate to cause micro pores (pit defects) on the surface of the wire, and when the pH is too high, Cu precipitates And excessive growth of copper (Cu) particles is promoted to cause unevenness on the surface of the wire, thereby deteriorating the appearance quality. In addition, there is a problem that the electric conductivity is lowered during welding, the electric resistance value is increased, and the wire feeding becomes unstable.

Therefore, in the present invention, it is preferable that the preferable P ratio and pH value of the plating bath satisfying the above-mentioned component composition satisfy 7.0 to 7.5 and 8.2 to 8.5, respectively.

On the other hand, in the case of performing plating using a plating bath satisfying the above-mentioned composition, it is preferable to maintain the plating bath temperature at the level of general management, that is, 50 to 60 DEG C, And then passed at a speed of 80 to 100 m / min. At this time, the immersion time of the wire is preferably controlled within 14.0 to 17.5 seconds.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the description of these embodiments is intended only to illustrate the practice of the present invention, but the present invention is not limited thereto. The scope of the present invention is determined by the matters set forth in the claims and the matters reasonably inferred from them.

( Example )

A wire (1.2 mm in diameter) plated with each of the plating solutions shown in Table 1 below was prepared and then welded with the above wire under the conditions shown in Table 2 below. At this time, the temperature of the plating bath was maintained at 55 占 폚, and the plating bath immersion time was 16.3 seconds, and the plating bath was passed at a rate of 90 m / min.

SM490 (Steel for Marine 490) was used as the base material for welding.

The plating quality (plating thickness, plating electrodepositability), surface roughness (centerline average surface roughness (Ra), average roughness (Rz)) and plating layer strength of the plated wire were measured and weldability (arc stability and transmittance ) Were evaluated and are shown in Table 3 below.

The strength of the plating layer was evaluated by scratch characteristics of the plated film using a micro & nano scratch tester without any measuring method and equipment since the plated coating was extremely thin. At this time, the micro (μ) scratch critical load range Lc is divided into 30 to 500 mN @ 10 μm (MST) and the nano scratch critical applied load range is 1 to 50 mN @ 10 μm (MST) The wear characteristics were evaluated quantitatively.

The wire surface quality was evaluated by measuring the centerline average roughness (Ra) and the average roughness (Rz) using a surface roughness meter.

The weldability was evaluated by evaluating the arc stability and wire feedability during welding using a welding monitoring device. The graphs of the measured welding current, welding voltage, feed rate and feed resistance were analyzed and evaluated. In case of low current (150A) welding arc cutting phenomenon was observed, arc stability in case of medium current (250A) welding, wire feeding ability in case of high current (350A) welding, and plating detachment degree were observed and evaluated.

division Plating solution P ratio pH value NH ₄ NO ₃ Concentration (g / l) Inventory 1 7.1 8.25 3.2 Inventory 2 7.1 8.3 4.5 Inventory 3 7.1 8.35 6.0 Honorable 4 7.1 8.4 7.5 Inventory 5 7.1 8.45 9.0 Inventory 6 7.3 8.3 3.5 Honorable 7 7.3 8.35 5.0 Honors 8 7.3 8.4 6.5 Proposition 9 7.3 8.45 8.0 Inventory 10 7.3 8.5 9.5 Exhibit 11 7.5 8.35 9.8 Inventory 12 7.5 8.25 9.0 Inventory 13 7.5 8.3 7.0 Inventory 14 7.5 8.45 5.0 Honorable Mention 15 7.5 8.47 3.2 Comparative Example 1 7.1 8.3 0 Comparative Example 2 7.3 8.4 0 Comparative Example 3 7.5 8.4 0 Comparative Example 4 6.7 8.4 2.2 Comparative Example 5 8.2 8.3 10.5 Comparative Example 6 7.3 8.3 2.2 Comparative Example 7 7.1 8.3 11 Comparative Example 8 7.5 8.3 10.5 Comparative Example 9 7.2 7.9 9.0 Comparative Example 10 7.1 9.0 9.5 Comparative Example 11 6.5 8.5 7.5 Comparative Example 12 7.9 8.4 7.5 Comparative Example 13 6.5 8.1 7.0 Comparative Example 14 8.0 8.6 7.0 Comparative Example 15 6.7 8.1 2.2 Comparative Example 16 7.7 8.6 10.5

Welding condition Welding posture Below view (1F) Welding technique Auto Carrige Welding condition DC reverse polarity (DCEP) Welding current Low current (150A) / Medium current (250A) / High current (350A) Wire extrusion length 20mm

division Plating property Surface roughness Plated layer strength Weldability evaluation
result Plated
Thickness (㎛) Plated
Electrodepositability RA
(탆) RZ
(탆) scratch
characteristic Arc
stability Transmittance Inventory 1 0.45 ○ 0.108 0.92 ◎ ○ ◎ ◎ Inventory 2 0.53 ◎ 0.122 1.45 ◎ ◎ ◎ ◎ Inventory 3 0.52 ◎ 0.132 1.24 ◎ ◎ ◎ ◎ Honorable 4 0.46 ◎ 0.154 1.72 ◎ ◎ ◎ ◎ Inventory 5 0.45 ○ 0.161 2.05 ◎ ○ ◎ ◎ Inventory 6 0.46 ◎ 0.123 1.44 ◎ ◎ ◎ ◎ Honorable 7 0.45 ◎ 0.136 1.49 ◎ ◎ ◎ ◎ Honors 8 0.45 ◎ 0.149 1.36 ◎ ◎ ◎ ◎ Proposition 9 0.53 ◎ 0.155 1.92 ◎ ◎ ◎ ◎ Inventory 10 0.46 ○ 0.169 2.27 ○ ○ ◎ ○ Exhibit 11 0.46 ◎ 0.138 2.38 ○ ○ ◎ ○ Inventory 12 0.54 ○ 0.094 2.11 ◎ ○ ◎ ◎ Inventory 13 0.54 ◎ 0.123 1.68 ◎ ◎ ◎ ◎ Inventory 14 0.45 ◎ 0.156 1.38 ◎ ◎ ◎ ◎ Honorable Mention 15 0.53 ○ 0.161 1.03 ◎ ◎ ◎ ◎ Comparative Example 1 0.46 △ 0.198 3.45 × × × × Comparative Example 2 0.46 △ 0.194 3.49 × × × × Comparative Example 3 0.54 × 0.201 3.47 × × × × Comparative Example 4 0.46 △ 0.196 3.06 △ △ × × Comparative Example 5 0.46 △ 0.195 3.05 △ × △ △ Comparative Example 6 0.53 × 0.208 3.14 × × × × Comparative Example 7 0.53 × 0.225 3.13 × × × × Comparative Example 8 0.53 × 0.217 3.06 × × × × Comparative Example 9 0.53 △ 0.185 2.93 △ △ △ △ Comparative Example 10 0.53 × 0.269 3.08 × × × × Comparative Example 11 0.54 × 0.242 2.85 × × × × Comparative Example 12 0.54 × 0.233 2.78 × △ × × Comparative Example 13 0.46 × 0.251 2.83 × × × × Comparative Example 14 0.46 × 0.186 2.72 × × × × Comparative Example 15 0.45 × 0.195 2.92 × × × × Comparative Example 16 0.54 × 0.259 3.03 × × × ×

(In Table 3, " Excellent "," Good "," Normal ", and " Bad "

In the case of Inventive Examples 1 to 15 using wires manufactured by plating with plating conditions satisfying the present invention, the plating layer was formed to a thickness of 0.45 to 0.55 mu m, so that no material metal was exposed and the plating quality was excellent. In addition, not only the surface roughness of the plating layer was excellent but also the feeding and feeding of the wire was excellent during welding, so that the plated layer was not dropped even when welding was performed at a high current of 350 A for a long time. This is because the strength of the plating layer adhered to the wire surface is sufficiently secured.

Fig. 1 (A) is a view of a section of the wire-plated layer of the inventive example 12, and Fig. 2 (A) shows that the plating layer is formed with a sufficient thickness as a result of observing the wire surface texture of the inventive example 1, It is also observed that the surface is smooth.

On the other hand, in the case of Comparative Examples 1 to 15 in which the plating conditions did not satisfy the present invention, it was confirmed that the plating properties were to be heated. For example, as a result of observing the cross section of the wire plating layer of Comparative Example 1 It was confirmed that a gap was formed between the surface and the plating layer, and the surface texture of the wire of Comparative Example 10 was observed (Fig. 2 (B)).

Therefore, when welding is performed using a wire having a reduced plating characteristic, the wire feedability is also affected, resulting in an increase in the wire feeding property at the time of welding at a high current of 350 A, and a part of the plating layer is removed.

Specifically, in Comparative Examples 1 to 3, the plating bath in which ammonium nitrate (NH ₄ NO ₃ ) was not added as proposed in the present invention was used, and although the plating layer was formed with sufficient thickness, the plating property and the plating layer strength were lowered The surface roughness of the wire surface was poor, so that the part of the plating layer was dropped during the middle- and high-current welding, and the wire feedability deteriorated.

In the case of Comparative Example 4, the P ratio of the plating solution and the concentration of ammonium nitrate (NH ₄ NO ₃ ) were insufficient to cause overgrowth of the plating particles on the wire surface, thereby increasing the surface roughness and scratched characteristics, And the transmittance was lowered.

In Comparative Example 5, since the P ratio of the plating solution and the concentration of ammonium nitrate (NH ₄ NO ₃ ) were excessive, diffusion of copper ion complex on the wire surface and increase of the reaction overvoltage increased the uniformity of the plating particles, As the plating time increased, the detachment of the plating film progressed and the scratch characteristics deteriorated. As a result, the plating layer fell off during welding and the feeding performance was lowered.

In Comparative Example 6, when the concentration of ammonium nitrate (NH ₄ NO ₃ ) in the plating solution was insufficient, the surface gloss of the plating surface was good due to the uniformity of the plating particles, but the plating layer strength was reduced by about 30% after 24 hours So that the feedability during welding deteriorated.

In the case of Comparative Examples 7 and 8 in which the concentration of ammonium nitrate (NH ₄ NO ₃ ) was excessive in the plating solution, the plating film was detached and the scratch characteristics of the plating layer deteriorated and the plating layer fell off during welding.

In Comparative Example 9, when the pH value of the plating solution was too low, the plating bath was decomposed by the hydration of pyrophosphate in the plating solution, and micropores were formed on the wire surface. On the other hand, in the case of Comparative Example 10 using a plating solution having an excessively high pH value, plating particles were excessively grown on the surface of the wire, resulting in smearing of the wire appearance, deteriorating the quality, and deteriorating the surface roughness.

In Comparative Example 11, when the P ratio of the plating solution was too low, the plating particles were excessively grown on the wire surface, and the surface roughness was remarkably lowered, resulting in poor weldability and feeding instability. Orthophosphate (Na ₃ PO ₄ ) And the contamination of the plating bath was serious, which resulted in a problem of a large increase in the production cost.

In Comparative Example 12, when the P ratio of the plating solution was excessively high, the strength of the plating layer was lowered, and the plating film was desorbed after plating.

Comparative Example 13 is a case where the P ratio and the pH value are insufficient in the range suggested by the present invention, and the plated particles are overgrown to deteriorate the plating property and the pit which is one kind of micro pores is generated on the surface of the wire, Example 14 shows that excessive P ratio and pH value causes overgrowth of the plating particles and copper precipitate is formed on the wire surface to deteriorate the appearance quality and the strength of the plating layer is lowered and the scratch characteristics are lowered, Arc interruption occurred frequently, and the wire delivery decreased due to the increase of the feeding resistance.

Comparative Example 15 is a case where the P ratio and the pH value of the plating solution are all insufficient and the concentration of ammonium nitrate (NH ₄ NO ₃ ) is insufficient and the plating ability is remarkably deteriorated, and plating particles are overgrown , Fine pores were generated and the quality of the wire surface deteriorated. In addition, the wire surface was roughened and the strength of the coating layer was lowered, resulting in poor weldability and poor wire feeding.

Comparative Example 16 is a case where the P ratio, the pH value, and the ammonium nitrate (NH ₄ NO ₃ ) concentration of the plating solution are all excessive, and the plating particles are overgrown on the wire surface to form precipitates on the surface, Quality deteriorated. In addition, during welding, part of the plating layer was dropped off and piled up on the welding tip, thereby deteriorating the wire feedability as well as the weldability.

On the other hand, Figure 3 is the observed wire surface of comparison without addition of plating bath in ammonium nitrate (NH ₄ NO ₃₎ an invention example 5 (A) and ammonium nitrate (NH ₄ NO ₃₎ was added Example 1 (B) As a result, when the present invention is satisfied, (A) shows a uniform surface roughness, whereas (B) in the case of using a plating bath to which ammonium nitrate (NH ₄ NO ₃ ) is not added causes poor surface roughness, Can be confirmed.

Fig. 4 shows scratch characteristics of Examples 2 (A) and 3 (B) evaluated. As a result, micro (μ) scratch characteristics were improved by 25 to 40% with the addition of ammonium nitrate (NH ₄ NO ₃ ) , And the nano scratch characteristics (micro wear characteristics) were improved by 12 to 30%. In addition, when the ammonium nitrate (NH ₄ NO ₃ ) was added, the surface deformation progressed to wear in the form of soft fracture, while in the case (B) where ammonium nitrate (NH ₄ NO ₃ ) And the phenomenon that the copper (Cu) plating layer was detached due to the shortage was observed.

Figs. 5 to 7 are graphs showing a welding monitoring measurement of Inventive Examples 3, 14 and 15 (A respectively) and Comparative Examples 9, 4 and 16 (B, respectively). Examples 3, 14 and 15 The welding current and the welding voltage waveform measured with low arc current (150A), medium current (250A) and high current (350A) were observed constantly and stable welding arc voltage and welding voltage waveform were observed constantly. And it was measured. On the other hand, in the case of Comparative Examples 9, 4 and 16, the arc was unstable under the same evaluation conditions, and the welding current waveform and the welding speed were irregular and the feeding resistance was increased.

Claims

A magnesium-based plating solution having a plating ratio of 3 to 10 g / l added ammonium nitrate (NH ₄ NO ₃ ) having a P ratio of 7.0 to 7.5 and a pH of 8.2 to 8.5, As a wire,
A center line average surface roughness of 0.05 to 0.20 mu m and an average roughness of 0.8 to 2.5 mu m.

delete

The method according to claim 1,
Wherein the plating is performed by passing the wire through the plating bath maintained at 50 to 60 DEG C at a speed of 80 to 100 m / min, and the wire deposition time is 14.0 to 17.5 seconds.